[Task]: Add add-on created datetime as a column to the content review queue

[wagnerand]

Description

While #15070 is being properly defined, we'd like to make a small change to the content-review queue to help with an ongoing event.

The created datetime of an add-on should be added as a column to the content-review. Also, both this new column and the existing last-updated column should be sortable.

We don't need to change the format of the values for either, so going with what we have (relative datetime to now) is fine.

Acceptance Criteria

### Milestones/checkpoints
- [ ] The content-review queue shows an additional column with the datetime of the add-on relative creation date.
- [ ] Both the new column and the existing last-updated column are sortable.
- [ ] Remove the "Flags" column from the content-review queue

Checks

• [X] If I have identified that the work is specific to a repository, I have removed "repository:addons-server" or "repository:addons-frontend"

┆Issue is synchronized with this Jira Task

[diox]

Implementation note: likely means get_content_review_queue() needs to stop ordering by created, that needs to be left to the ContentReviewTable (which needs to be orderable = True, to have a default_order_by and and possibly some restrictions added to columns we don't want to allow sorting by)

[wagnerand]

The other columns available are:

• Add-on: does not need to be sortable
• Flags: does not need to be sortable. We might even just remove that, I don't think the flags we have a very relevant for content-review, but we can do that in a followup.